1. FIELD OF THE INVENTION
The present invention relates to frequency stabilized electronic oscillators, and more particularly to such oscillators having resonators fabricated from a superconducting material for use in applications where small size and light weight are important.
2 DESCRIPTION OF BACKGROUND ART
It is known to use an oscillating means that employs dielectric resonators coupled to an active element to improve stability. Such dielectric resonators provide high-Q performance but are large and heavy. For example, U.S. Pat. No. 4,565,979, issued to Fiedziuszko, discloses a double dielectric resonator tuned by means of a screw. Such a device contains bulky mechanical elements and cannot be fabricated by an integrated circuit process.
Japanese Patent publication 61-285804 discloses an oscillating means that comprises a resonant metallic cavity coupled to the remainder of the oscillating means circuit through two coupling holes. Such a cavity stabilized oscillating means is also large, heavy and expensive to manufacture. Size and weight are critical in space applications, such as satellites. Therefore, the bulky oscillating means described in this publication is not well suited to such applications.
U.S. Pat. No. 4,749,963, issued to Makimoto et al., shows a C-shaped stripline ring structure forming a portion of a stabilizing resonator of an oscillating means. The C-shaped stripline ring is used to provide only the inductive portion of the resonator. The resonator comprises additional capacitive circuitry across the open ends of the C-shaped stripline ring. The insertion of the capacitor results in degraded performance (lower Q). The structure described by Makimoto et al. is, therefore, not suited to superconductor implementation.
Other references are U.S. Pat. Nos. 4,149,127; 4,187,476; 4,219,779; 4,307,352; 4,331,940; and 4,481,486.